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authorMasahiro Yamada <yamada.masahiro@socionext.com>2018-05-28 18:21:55 +0900
committerMasahiro Yamada <yamada.masahiro@socionext.com>2018-05-29 03:31:19 +0900
commit915f64901eb3f1e4e126f58c0d2f82f5ec1d1223 (patch)
treeff55db36fc7f90bcc51af0070bc65ac947737c4d /scripts
parenta702a6176e2fea9ae366a7345247eb886e4cc730 (diff)
downloadlinux-stericsson-915f64901eb3f1e4e126f58c0d2f82f5ec1d1223.tar.gz
kconfig: error out if a recursive variable references itself
When using a recursively expanded variable, it is a common mistake to make circular reference. For example, Make terminates the following code: X = $(X) Y := $(X) Let's detect the circular expansion in Kconfig, too. On the other hand, a function that recurses itself is a commonly-used programming technique. So, Make does not check recursion in the reference with 'call'. For example, the following code continues running eternally: X = $(call X) Y := $(X) Kconfig allows circular expansion if one or more arguments are given, but terminates when the same function is recursively invoked 1000 times, assuming it is a programming mistake. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Diffstat (limited to 'scripts')
-rw-r--r--scripts/kconfig/preprocess.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
index 0574039238c6..65da87fce907 100644
--- a/scripts/kconfig/preprocess.c
+++ b/scripts/kconfig/preprocess.c
@@ -229,6 +229,7 @@ struct variable {
char *name;
char *value;
enum variable_flavor flavor;
+ int exp_count;
struct list_head node;
};
@@ -253,11 +254,22 @@ static char *variable_expand(const char *name, int argc, char *argv[])
if (!v)
return NULL;
+ if (argc == 0 && v->exp_count)
+ pperror("Recursive variable '%s' references itself (eventually)",
+ name);
+
+ if (v->exp_count > 1000)
+ pperror("Too deep recursive expansion");
+
+ v->exp_count++;
+
if (v->flavor == VAR_RECURSIVE)
res = expand_string_with_args(v->value, argc, argv);
else
res = xstrdup(v->value);
+ v->exp_count--;
+
return res;
}
@@ -284,6 +296,7 @@ void variable_add(const char *name, const char *value,
v = xmalloc(sizeof(*v));
v->name = xstrdup(name);
+ v->exp_count = 0;
list_add_tail(&v->node, &variable_list);
}